Estimate how long the Sun would last if it were merely a huge fire that was releasing chemical energy. Assume that the Sun begins with roughly 108 joules per kilogram, a chemical energy content typical of atomic matter. You will need both the mass and luminosity of the Sun to do the calculation.

You don't need to worry about this solar death anytime soon, though. Inside the sun, a churning fusion engine fuels the star, and it still has a lot of fuel left — about 5 billion years' worth.

Astronomers estimate that the sun has about 7 billion to 8 billion years left before it sputters out and dies. Humanity may be long gone by then, or perhaps we'll have already colonized another planet. Additional resources: Find out what will happen to the Earth when the sun dies, from Live Science.

The studies suggest that the solar system’s planets will continue to orbit the Sun stably for at least 40 million years. But after that, they show there is a small but not insignificant chance that things could go terribly awry.

In one of Batygin and Laughlin’s simulations, Mercury was thrown into the Sun 1.3 billion years from now. In another, Mars was flung out of the solar system after 820 million years, then 40 million years later Mercury and Venus collided.

Explanation:

42.42 km/h

Explanation:

We are required to calculate the average speed between 2.8 km and 4.2 km.

We will need to calculate the average rate of distance between 2.8 km and 4.2 km.

We will divide the distance change by change in time.

Average speed =

Distance change = 4.2 km - 2.8 km

                            = 1.4 km

Change in time = 0.084 h - 0.051 h

                          = 0.033 h

Therefore;

Average speed = 1.4 km ÷ 0.033 h

                          = 42.42 km/h

Therefore, the average speed between 2.8 km and 4.2 km is 42.42 km/h